(a) Field of the Invention
This invention relates to novel 1-oxo-5H-pyrimido[2,1-c][1,4]benzoxa(or thia)zine-2-carboxylic acid lower alkyl esters, to derivatives thereof, to therapeutically acceptable basic addition salts thereof, to process for the preparation and to pharmaceutical compositions. The compounds of this invention are useful in the treatment of anaphylactic reactions and allergic conditions in mammals.
(b) Description of the Prior Art
A search of the chemical literature indicates that the compounds of this invention represent a novel tricyclic ring system. A number of related tricyclic compounds are described in the following reports: S. B. Kadin, U.S. Pat. No. 4,017,625, issued May 24, 1976; S. B. Kadin, U.S. Pat. No. 4,066,766, issued Jan. 3, 1978; and S. B. Kadin and P. F. Moore, U.S. Pat. No. 4,031,217, issued June 21, 1977. These references disclose compounds which, like the compounds of this invention, are tricyclic; however, the tricyclic compounds in these references differ by being "carba" analogs.